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A growing number of states are trying to crack down on voter fraud by requiring photo identification at polling booths or by using a federal database to weed out immigrants.

The tactics have come under scrutiny in the run-up to the fall election season, in which President Barack Obama, a Democrat, and Republic candidate Mitt Romney are running neck and neck.

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Democrats accuse Republicans of trying to make voting more difficult for the poor, black and Latino populations, which typically lean Democratic. Republicans say they're simply trying to enforce the law, and charge that Democrats are too lax on the issue.

In the past year or so, 10 states – Pennsylvania, Texas, Alabama, Georgia, Indiana, Mississippi, South Carolina, Tennessee, and Wisconsin -- have passed new laws requiring citizens to show photo ID before they vote, according to a study released this week by the Brennan Center for Justice in New York. While nine out of 10 Americans have valid ID cards, the proportion is much lower among African-Americans, Latinos and the elderly, the study asserted. Many have a hard time obtaining an ID because they have to rely on spotty public transportation to travel long distances to reach government offices. These offices are rarely open at nights or on weekends.

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“It is wrong to enact laws to make it harder for some Americans to vote,” Brennan Center president Michael Waldman said in a preface to the report.

In Pennsylvania, Democrats have fought that state's new law as politically motivated, NBC Philadelphia reported. They point to comments by Republican House Leader Mike Turzai, who claimed publicly that the changes would allow Romney to win the state.

At the same time, several states have petitioned the U.S. Department of Homeland Security to use a federal database that contains information about immigrants who are in the country legally. The information, originally intended to identify immigrants who are eligible for public benefits, would be used by the states to remove from voter rolls those who are not naturalized citizens.

Florida, which has a large Latino immigrant population, led the charge on that front, successfully suing the DHS for access to the database, NBC Miami reported. Emboldened by Florida’s win, several other states are pushing for access as well. They include Colorado, New Mexico, Nevada, Michigan and Ohio, all considered battleground states in the presidential election.

Florida Gov. Rick Scott has come under fire from the Department of Justice for trying to purge non-citizens from the state’s voter rolls. The Voting Rights Act of 1965 requires Florida to seek federal approval before making such changes. Scott has said the moves are meant to eliminate illegal voting, not to target minorities.